There was a thread discussing the gearbox and transfer breathers. Conclusion is that there is still an entry even if you locate the obvious breather but should be ok as long as you don't roll upside-down whilst submerged. So I've not bothered with the tranny and transfer, just the diffs.

Try http://faq.out-club.ru/ for the workshop manual. It only goes up to 2013 NW but is still primarily relevant for the NX.